Recently, a nitride semiconductor which is broadly used as a base material of a light emitting diode is fabricated by growing the nitride semiconductor on a homogeneous substrate such as a gallium nitride substrate or a heterogeneous substrate such as a sapphire substrate. However, since gallium nitride has a melting point of 2,000° C. or higher and a very high nitrogen vapor pressure, it is difficult to fabricate an ingot of gallium nitride. Accordingly, the nitride semiconductor is generally grown on a heterogeneous substrate such as a sapphire substrate, a silicon carbide (SiC) substrate, a silicon (Si) substrate, or the like.